In general, a diesel engine as internal combustion engine employs not plug spark ignition like a gasoline engine but natural ignition through direct injection of light oil as fuel into air which has been high-temperatured through high compression.
For a diesel engine, attention is recently paid to a so-called premixed compression ignition strategy for injection of fuel at high pressure and before a top dead center of a piston stroke so as to premix the fuel with air, the fuel-air mixture being compressed into high temperature to cause autoignition and combustion in a single burst.
In order to implement the premixed compression ignition strategy, a diesel engine with fuel such as light oil being injected midway of an intake passage is being developed.
State-of-the-art technology for a premixed compression ignition engine with fuel being injected midway of an intake passage is disclosed, for example, in Patent Literature 1.                Patent Literature 1: JP 2007-24001A        